Heart failure is a deadly epidemic with few therapeutic options. Ventricular restraint represents a promising non-transplant treatment currently in clinical trials. In this surgery, the heart is wrapped with passive material to prevent it from dilating and remodeling. Currently, there is no methodology to measure or adjust restraint therapy level. No studies exist correlating restraint level to therapy efficacy or mechanism. Therapy is applied subjectively. This may ultimately limit overall effectiveness and impair safety. To address this, an adjustable, fluid-filled balloon was developed to quantitatively apply restraint to the entire ventricular epicardial surface. The long-term goals of this project are to quantitate how ventricular restraint influences the remodeling process and to identify rational criteria for improved therapy efficacy by applying restraint in a measurable and adjustable manner. By applying measurable, adjustable restraint with this unique restraint device to an ischemic ovine model of dilated cardiomyopathy, Specific Aim #1 will measure the acute and subacute effects of restraint level on remodeling pathophysiology. In Specific Aim #2, the chronic effects of restraint on remodeling will be quantitated, and an optimal restraint level will be identified. Specific Aim #3 will investigate whether measurable, adjustable restraint therapy results in increased reverse remodeling compared to standard, non-adjustable restraint therapy. These specific aims are designed to provide a comprehensive quantification of the effect of restraint level on ventricular pathophysiology and remodeling. By measuring cause and effect with respect to restraint and reverse remodeling for the first time, these studies may provide an entire new approach to ventricular restraint that may lead to significant advance in the armamentarium against heart failure. Heart failure is an epidemic with few therapeutic options. Ventricular restraint is a promising non-transplant surgical option currently in clinical trials. This proposal seeks to better understand and improve restraint therapy for patients by adjusting and measuring the applied restraint level.